body {
    width: 100%;
    max-width: 640px;
    min-width: 320px;
    margin: 0 auto;
    font-family: -apple-system,Helvetica,sans-serif;
    font-size: 14px;
    color: #666;
    line-height: 1.5;
    background-color: #ccc;
}
.clearfix:before,
.clearfix:after {
    content: " ";
    display: table;
}
img {
    /* 去除图片下面的空白缝隙 */
    vertical-align: middle;
}
a {
    text-decoration: none;
    color: #666;
}
.app {
    width: 100%;
    height: 45px;
}
ul {
    margin: 0;
    padding: 0;
}
.app ul li {
    float: left;
    height: 45px;
    background-color: #333;
    list-style: none;
    text-align: center;
    line-height: 45px;
    color: #fff;
}
.app ul li:nth-child(1) {
    width: 8%;
}
.app ul li:nth-child(1) img{
    width: 10px;
}
.app ul li:nth-child(2) {
    width: 10%;
}
.app ul li:nth-child(2) img{
    width: 30px;
    /* 图片默认和文字是基线对齐，要设置为居中对齐 */
    vertical-align: middle;
}
.app ul li:nth-child(3) {
    width: 57%;
}
.app ul li:nth-child(4) {
    width: 25%;
    background-color: #F53413;
}
/* 搜索 */
.search-wrap {
    /* 防止内部的search外边距合并,就使用overflow:hidden */
    overflow: hidden;
    position: fixed;
    width: 100%;
    min-width: 320px;
    max-width: 640px;
    height: 44px;
}
.search-btn {
    position: absolute;
    top: 0;
    left: 0;
    width: 40px;
    height: 44px;
}
.search-btn::after {
    position: relative;
    content: "";
    display: block;
    width: 20px;
    height: 18px;
    background: url(/images/s-btn.png) no-repeat;
    background-size: 20px 18px;
    margin: 14px 0 0 15px;
}
.search-login {
    position: absolute;
    top: 0;
    right: 0;
    /* background-color: purple; */
    width: 40px;
    height: 44px;
    line-height: 44px;
    font-size: 14px;

}
.search {
    position: relative;
    height: 30px;
    background-color: #fff;
    border-radius: 15px;
    margin: 7px 50px 0;
}
.jd-icon {
    position: absolute;
    top: 7px;
    left: 12px;
    width: 20px;
    height: 15px;
    background-color: pink;
    background: url(/images/jd.png);
    background-size: 20px 15px;
}
.jd-icon::after {
    position: absolute;
    top: 1px;
    left: 27px;

    content: "";
    /* 伪元素为行内元素,要转换为块元素,才能设置宽高 */
    display: block;
    width: 1px;
    height: 15px;
    background-color: #333;
}
.sou {
    position: absolute;
    top: 8px;
    left: 47px;

    width: 18px;
    height: 15px;
    /* 二倍精灵图的做法 */
    background: url(/images/jd-sprites.png) no-repeat -83px 0px;
    background-size: 200px 200px;
}
/* 主体内容部分 */
.slider img{
    width: 100%;
}
nav a {
    float: left;
    width: 20%;
    /* text-align: center;让其内部的图片和文字都居中对齐 */
    text-align: center;
}
nav a img {
    width: 50%;
    margin: 10% 10% 0 10%;
}
nav a span {
    /* 将其转换为块元素，使其变到下一行显示 */
    display: block;
}
/* 新闻快报模块 */
.news {
    width: 100%;
    padding-top: 100px;
}
.news a {
    float: left;
    box-sizing: border-box;
}
.news a:nth-child(1) {
    width: 50%;
}
.news a img {
    width: 100%;
}
.news a:nth-child(n+2) {
    width: 25%;
    border-left: 1px solid #ccc;
}